Formula design of rigid PVC drainage pipe

UPVC pipe is also called rigid PVC pipe. It is an amorphous thermoplastic vinyl chloride resin that is formed by adding certain additives (such as stabilizers, lubricants, fillers, modifiers, etc.) and then processed into pipes by an extrusion machine. Let's see the PVC pipe making formula together.

UPVC hard tube formula

PVC (SG-5) + stabilizer (lead salt, metal soap) + lubricant + processing aid + pigment

Formula components

1.PVC resin      

In order to obtain rapid and uniform plasticization, a suspension type loose resin should be used, and the resin types are SG-5.

Note: S indicates that PVC resin is made by suspension method, G indicates general-purpose resin and SG-5 is mostly used for transparent products, rigid pipes and profiles.

2. PVC stabilizer     

Pure PVC resin is extremely sensitive to heat. When the heating temperature exceeds 90 ° C, a slight thermal decomposition reaction will occur; when the temperature rises to 120 ° C, the decomposition reaction will intensify; at 150 ° C for 10 minutes, the PVC resin will change from the original The white gradually turns into yellow-red-brown-black. The decomposition process of PVC resin is a series of chain reactions caused by the de-HCL reaction, and finally causes the macromolecular chain to break.

3. Lubricant

PVC melt has a high tendency to adhere to metals, and the friction between the melt and between the melt and the processing equipment is large. Lubricants need to be added to overcome friction resistance. The amount of lubricant added is relatively large.

According to the different compatibility of lubricant and PVC resin, it can be divided into internal lubricant (good compatibility) and external lubricant (poor compatibility).

(1) metal soap (external lubricant)

Metal salts of higher fatty acids (commonly known as metal soaps) are one of the commonly used lubricants. In addition to its lubricating effect, it is also a heat stabilizer for PVC. For the saponification of a certain metal, the longer the carbon chain of the bonded fatty acid, the better its lubricity. Commonly used are calcium stearate, zinc stearate, lead stearate, etc. Among them, lead stearate has the best lubricity.

(2) Polyethylene wax (internal lubricant)

PE wax is also called polymer wax. As a lubricant, PE wax has stable chemical properties and good electrical properties. Compared with other external lubricants of PVC, polyethylene wax has a stronger internal lubrication effect.

4. Filler

Solid matter added to the material to improve performance or reduce cost. Organic, inorganic, metallic or non-metallic powders that are normally free of water, neutral and do not adversely affect material components can be used as fillers.

Calcium carbonate can play a skeletal role in plastic products, which has a great effect on the dimensional stability of plastic products, can increase the hardness of the products, and can also improve the surface gloss and surface flatness of the products. Adding calcium carbonate to general plastic products can improve the heat resistance. Since calcium carbonate has a whiteness of more than 90%, it can also replace expensive white pigments to play a certain whitening effect.

With continuous focusing on plastic extrusion machinery, Jiangsu Xinrongplas Machinery has gained a certain awareness as one of professional PVC pipe extrusion line manufacturer.